平板上环形液滴在电场-热毛细耦合效应下的动力学特性研究

The structure with circular free surface on solid substrate has wide applications in 3D printing, it has received extensive attentions in the fields of fluid mechanics and biomedicine. Liquid ring deposited on solid substrate is frequently encountered in engineering process, but the structure is difficult to be controlled due to the unstable flow behavior and unclear physical mechanisms, which remains big challenges in printing technologies. Therefore, we need to develop a new model to study the dynamic characteristic of liquid ring on solid substrate. In this proposal, we focus on the abovementioned systems with complex morphology to explore the flow instability phenomenon. In order to address the uncontrollable complex fluid morphology problem, we systematically investigate the coupling mechanisms of electrical and thermocapillary effects for an annular liquid ring on a substrate using experimental and numerical methods. On the basis of long wave theory, the physical model is developed by simplifying initial equations. Then, we able to solve the linear stability and nonlinear evolution of the equations by Chebyshev-Fourier spectral method. By elucidating the underlying physics of flow instability, we experimentally characterize the flow patterns to interpret the mechanisms of ring formation, breakup and nonlinear evolution. Finally, we further analyze the dynamics under the external forces regarding electrical and thermocapillary effects, eventually achieving the precise regulation of the flow behavior of liquid ring. Our project enriches the thermodynamics and electrodynamics theory of liquid ring on the substrate, and has a great scientific application potential for the next generation advanced manufacturing technology.

固体基底上具有环形自由界面的结构在3D打印中有广泛的应用前景，是当今流体力学、生物医学等交叉学科的研究热点。这些复杂的形貌（如：平板上环形液滴）是工程应用中较为常见的结构，但由于其蕴含丰富的流动不稳定特性和尚不明确的物理机制，导致其形貌难以控制，给打印技术的实际应用带来了巨大的挑战和困难。因此，亟待发展新模型来研究平板上环形液滴的动力学特性。本项目针对液环的流动失稳现象，拟采用实验研究和理论分析的方法研究平板上环形液滴电场-热毛细效应耦合机理，解决复杂流体形貌不可控问题。将在长波理论框架下建立物理模型，采用Chebyshev-Fourier谱方法求解界面长波演化方程的线性稳定性和非线性演化规律，量化流动失稳的临界参数和流态的变化规律。基于理论分析结果，拟开展平板上环形液滴的动力学特性实验研究，揭示具有复杂自由界面流体的成环机理、断裂机制和非线性演化规律。在此基础上，考虑外力的作用（电场和热毛细力），探究电场、热毛细及其耦合效应对液环流动不稳定性的影响，最终实现对液环流动行为的精确调控。研究成果将进一步丰富和完善平板上环形液滴的热-电动力学理论，对新一代先进制造技术有重要的应用价值。

固体基底上具有环形自由界面的结构在3D打印中有广泛的应用前景，是当今流体力学、生物医学等交叉学科的研究热点。平板上环形液滴是工程应用中较为常见的结构，但由于其蕴含丰富的流动不稳定特性和尚不明确的物理机制，给打印后的固化带来了巨大的挑战和困难。因此，亟待发展新模型来研究平板上环形液滴的动力学特性，解决平板上液环流动失稳导致的固化形貌不可控的问题。本项目围绕环形液滴的成环机理、断裂机制和调控规律等关键科学问题，开展了平板上环形液滴电场-热毛细效应耦合机理研究。搭建了平板上环形液滴的实验平台，突破了关键实验技术，设计了一种环形密封结构制备装置、液-液相体系的表面张力装置及其操作软件。通过实验研究了外力作用下平板上液环的成环机理、断裂机制和动力学演化规律，揭示具有自由界面流体的热-电动力学耦合机理。开发了平板上环形液滴的数值模型，求解环形液滴的断裂过程和非线性演化规律。探究了电场、热毛细及其耦合效应对液环流动不稳定性的影响，最终实现对液环流动行为的精确调控。研究成果将进一步丰富和完善平板上环形液滴的热-电动力学理论，对新一代先进制造技术有重要的应用价值。